Many portable electronic devices exist today for consumers. In fact, many consumers carry multiple portable devices such as music players, cellular telephones, personal data assistants, smartphones such as those marketed as a Blackberry by Research In Motion, Inc., portable global positioning system devices, etc. These portable devices are powered by a rechargeable, on-board battery.
In order to charge the battery, the portable device (or possibly just the battery thereof) is connected to a power device. Typically, the power device is a combination of a charger and a power adapter so that alternating current with an input voltage is received and converted to direct current, and the voltage is stepped-down to an output voltage for which the battery is designed. It should be noted that, depending on source power and output power requirements, the power device need not always convert and step, instead being able to do one or the other, such as may be the case for a DC-DC adapter used only to step-down the input voltage to an output voltage or simply receiving input power and delivering output power to the battery.
The power device typically has a first end with a pair of prongs that are received in and connected to a receptacle of a power outlet, and has a cable extending from the first end to a second end, the second end having a connector for electrical connection with the portable device. The power device also typically includes internal circuitry for the power conversion and stepping, and this circuitry requires an enlarged portion (enlarged relative to the cable of the power device). The enlarged portion is typically located at or adjacent the first end, though it may be inline and between the first and second ends or be located at the second end such as in a desktop-style or cradle-type charger.
Regardless of the configuration, the usage of the power device is almost uniformly identical. Specifically, a user connects the first, prong-bearing end of the power device with a receptacle, such as a receptacle of a wall-oriented/mounted power outlet. The power device second end is placed in a convenient place for the user to reach, and the portable device is connected to the second end when recharging is needed or desired, commonly on a daily basis at the end of a day. When the user desires to use or carry it, the portable device is disconnected from the power device, and the second end is left in the convenient place. Rarely, if ever, does the user think to unplug the power device from the receptacle. One of the reasons for this is that receptacles are typically behind furniture or in another location that is difficult to reach, or it is just too much trouble to unplug when it is known that it will need to be plugged in again a relatively short period of time.
There is a growing but still largely unappreciated recognition by users that leaving the power device plugged in allows the power device to continue to draw current or power from the receptacle despite no portable device being connected therewith. This power draw is referred to as phantom load. To be more precise, phantom load is residual power consumption by power devices when not connected to their host electronic device, or when the electronic device is shut off.
Phantom load is becoming a greater issue for the public. Electrical devices that result in the described phantom load are continually increasing in per capita usage, populations increase exponentially, and great portions of the world's population are gaining the discretionary capital that enables the purchase of such devices. Energy is becoming more expensive on a monetary basis, and energy production overwhelmingly has an environmental impact, such as fossil fuel or nuclear energy.
Extensive effort has been and continues to be put into development of energy-efficient devices of all sorts. The “Energy Star” program sponsored by the United States Environmental Protection Agency and the United States Department of Energy is well known, though principally for energy efficiency appliances and building products such as glass doors and windows. In parallel with Energy Star standards efforts, a variety of state and federal laws have been enacted that are directed toward external power-supply products, which includes power devices or chargers for portable electronic devices. The most-recent standard for such portable devices is version 2.0 and is considered a push beyond simply forcing the industry to use power efficient components and layouts, requiring more complex power devices and supplies.
A recent development that arose during the preparation of the present application is a prototype device from Nokia that operates with a mechanical switch. Specifically, the Nokia device has a first end receivable in a power receptacle and including a housing for internal circuitry that provides the charger/adapter functions. The Nokia device is turned on by depressing a button on the housing; when the internal circuitry recognizes the electronic device is fully charged, the button is released and the Nokia device is turned off.
While it is believed to have been developed after conception of the invention of present application, the Nokia device highlights some interesting points about efforts in this arena. For instance, the button of the Nokia device is a mechanical button and requires some type of mechanism for releasing the button for the “off” state. The button is also located on a housing for the internal circuitry that is separate from the electronic device connector, the connector being a two-terminal device (that is, having “+” and “−” terminals). The Nokia device also requires some type of mechanism for determining when the device should be shut down.
As discussed above, most people do not bother to unplug their power devices when they remove the portable electronic device therefrom. The Nokia device certainly relieves a user from having to plug and un-plug the device, but it still requires a user to reach to wherever the device is received in a receptacle in order to turn on the device.
In order to be a true “zero-energy” device, the power input (i.e., AC input) to the power device must be cut. That is, the point in the power device circuitry where the circuit is broke is important: a switch or the like simply on a end-point terminal of the power device may cut the power being delivered to an electronic device connected thereto that is fully charged, but, such allows the internal circuitry to draw power so that the effect of such would be no different than simply removing the electronic device itself.
Towards this end, the Nokia device displays a uniform manner of thinking in the industry: a switch for connecting or disconnecting the AC power must be co-located with or closely proximate to the AC input such as the power prongs.
Accordingly, it is desirable and there is a need for an improved power device, charger or otherwise, for reducing phantom load when a portable electrical device is disconnected from the power device or otherwise not intended to be drawing power from the power device.